Welding apparatus



I Sept. 21, 1943.

H. T. PLATZ 2,329,351

WELDING APPARATUS Filed March 30, 1942 5 Sheets-Sheet '1 Ill 50/211414Ilr 1 0/10 Sept. 21, 1943. H. T. PLATZ WELDING APPARATUS Filed March 30,1942 5 Sheets-Sheet 2 rIIlI INVENI'OR. flew rip/MW,

l ATTORNEY zrlunr O u 10 i d/emlq'llryclvc.

Q a l? Sept. 21, 1943. PLATZ I 2,329,851

WELDING APPARATUS Filed March 50, 1942 5 Sheets-Sheet 3 INVENTOR.

Hes/p 7710/2205 P/aZz ATTORNEYS.

Sept. 21,1943. T, P TZ 2,329,851

WELDING APPARATUS Filed March 30, 1942 5 Sheets-Sheet 4 INVENTOR.

Henp/ 7770/2205 P/alz A RNEY Sept. 21, 1943. PLATZ 2,329,851

' WELDING APPARATUS Filed March 30, 1942 5 Sheets-Sheet 5 INVENTOR. Hwy7710mm P/alz Y I 9 M W 0mm Patented Sept. 21, 1943 WELDING APPARATUSHenry Thomas Plats, Detroit, Mich., assignor to Briggs ManufacturingCompany, Detroit, Mich., a corporation of Michigan Application March so,1942, Serial No. 436,871

Claims.

operation.

The above feature renders it possible to appreciably increase the rateoi production of welded plates having spaced raised portions or ribs ofa height exceeding the normal electrode travel required for ordinarywelding because'it enables restricting the normal electrode travel to aminimum during successive ordinary welding operations and permits rapidraising of the .electrode beyond its normal travel suiiiciently to clearribs or raised portions on the plates when such are encountered.

With the above, as well as other objects inview. this invention residesin the novel means provided for selectively raising the electrode bevondits normal restricted travel and this means together with other featuresof the invention will be made more apparent as this descriptionproceeds. especially when considered in connection with the accompanyingdrawings, wherein: Figure l is a fragmentary side elevational view of awelder embodying the features or this invention;

F g re 2 is a fragmentary vertical sectional view of the welder shown inFigure 1;'

Figure 3. is a diagrammatic view showing the various controls for thewelder;

Figure 4 is a detail sectional view of the vertical guide for the welderhead;

Figure 5 is a detail sectional view oi. the vertical guide for themovable electrode;

Figure 6 is a cross sectional view taken on the lineHofFigurel; p

Figure '1 is a cross sectional view taken on the lineI-l ofFigure 1; and

Figure 8 is a diagrammatic view showing the application of the welder toa typical work piece.

The welder selected for the purpose 0! illustrating the invention is astationary spot welder having a vertically reciprocableelectrodenorvanally rnovable throughout a range of travel which is restricted toreduce lost motion between successive welds to a minimum. The movableelectrode is designated in the drawings by the re!- erence II and thenormal restricted the head 2!.

.ably engages the inner wall of the sleeve i1 travel of the electrode isdesignated in Figure 8 by the-reference character ii. This restrictedrange of movement of the electrode i0 is sumcient to satisfactorily weldthe work I! but is less than the height of the rib. l3 on the work. Inorder to enable the welding operations to be continued at the oppositeside of the rib without seriously delaying these operations, I providemeans for expediently retracting the-electrode it throughout a distanceIt which is shown in Figure 8 as being suflicient to enable the rib l3to be passed beneath the electrode l0.

With the above in mind reference will now be made more in detail to theparticular construction oi the welder and to the specific means providedherein for selectively moving the electrode in through the range oftravel indicated by the reference character It in Figure 8. Uponreference to Figure 2 of the drawings it will be noted that thereference character It designates a vertically disposed cylinder closedat its upper end and having a radially outwardly extending attachingflange It at its lower end. The cylinder I5 is carried by a verticallyslidable sleeve II concentrically arranged with respect to the axis ofthe cylinder and having a radially outwardly extending flange it at theupper end secured to the flange It by means of fastener elements i9.

A piston 20 is mounted in the cylinder ii for reciprocation and isprovidedwith a head 2| of I sufficient diameter to slidably engage theinner g wall of the cylinder it. The head 2| is mounted on the upper endof a skirt 22 having an external diameter less than the internaldiameter of the cylinder to provide an annular chamber 23 below Thelower end of the skirt 22 slidand the inner wall of the skirt forms abearin for the enlarged upper end 24 of a vertical plungwardly extendingshoulder 21 formed on the lower end of the piston skirt 22.

The two shoulders are normally yieldably held in engagement with oneanother by means or a coil spring 2| having the upper end abutting theunderside of the piston head 2| and having the lower end seated on aplate 2! carried by the head 24 of the plunger 2'. The upper end of thecoil spring is held against shifting movement relative to the piston bymeans oi. an annular fi lse at extending downwardly from the piston headand surrounding the upper end of the coil spring. The lower endportionof the coil spring is held in position relative to the plunger by meansof an annular retainer 3| having its lower end secured to the plate 29and having the upper end secured to the corresponding end of the plungerby a ring 32.

The spring 28 operatively connects the piston 20 to the plunger 25 andis of sufficient strength to. move both of these elements as a unitunder the action of the fluid pressure admitted to the upper end of thecylinder by the control mechanism to be more fully hereinafterdescribed. The plunger 25 is guided'in the sleeve I! by means of asecond sleeve 33 having the inner and outer surfaces respectivelyslidably engaging the outer and inner surfaces of the plunger 25 andsleeve IT. The lower ends of both the plunger 25 and sleeve'33 aresecured to a plate 34 by means of bolts 35. The plate 34 is positionedbelow the lower end of the sleeve Hand is detachably secured to theelectrode ID by means of bolts 35.

It follows from the above that downward movement of the piston 20 in thecylinder I imparts a corresponding movement to the plunger 25 and sleeve33. Inasmuch as the electrode I0 is secured to the lower ends of theplunger 25 and sleeve 33, the electrode is also moved in a downwarddirection into engagement with the work I2 to be welded. As soon,however, as the electrode engages the work l2, the coil spring 28 iscompressed and the piston moves downwardly relative to the plunger andsleeve 33. The extent of downward movement of the piston 20 relativeto'the plunger 25 and sleeve 33 depends upon the amount of clearance 31provided between the lower end of the piston skirt 22 and the upper endof the sleeve 33. Engagement of the lower end of the piston skirt 22with the upper end of the sleeve 33 establishes a positive connectionbetween the piston 20 and the electrode ID with the result that theelectrode is subjected to the full line pressure. This phase of theoperation is usually the period when the weld is forged and is importantin obtaining strong commercially satisfactory welds.

Upon completion of the welding operation, the upper end of the cylinderI5 is ultimately exhausted and, in. the present instance, the parts arereturned to their restricted positions by a constant pressure which ismaintained in the annular space 23 surrounding the piston skirt. Itwill, of course, be understood that the pressure in the annular space 23acts on a much smaller area of the piston head 2| than the pressurewhich is introduced into the upper end of the cylinder and, therefore,does not interfere with the operation of the piston by the latterpressure. The escape of fluid under pressure from the chamber 23 isprevented by the cooperation of the sealing rings 38 and 39.

As pointed out above, the range of travel of ,the electrode II) by themechanism previously plunger 25, sleeve 33 and electrode l0 tosubstantially increase the clearance between the lower end of theelectrode l0 and the work l2. The above listed parts are selectivelyraised and returned to their normal positions by the sleeve I. Indetail, a double acting piston 4|] is secured to the sleeve intermediateits ends and is slid-'- ably supported in a cylinder 4|.

The cylinder 4| is concentrically supported with respect to the sleeveI1 and is welded or otherwise permanently secured to a bracket 42 whichis flxed in any suitable. manner on the frame structure of the welder.Upon reference to Figure 2 it will be noted that the cylinder 4| isprovided with a liner 43 engageable with the piston 4|! to guide thelatter and insulated from metallic contact with the cylinder 4| by meansof. the insulating material 44. As a result, any

electrical current which may escape from the electrode is prevented frompassing through the stationary supporting bracket.

The upper end of the cylinder 4| isclosed by a bearing 45 having asliding engagement with the outer surface of the sleeve I! and having aradially outwardly extending attaching flange 46 which is secured to theupper end of the cylinder 4| by bolts 41. The lower end of the cylinder4| is closed by a bearing 48 which slidably engages the outer surface ofthe sleeve H and is secured to the lower end of the cylinder 4| in thesame manner as the bearing 45.is secured to the upper end of thecylinder. Both of the bearings cooperate to slidably support the sleevel1 and fluid pressure is prevented from escaping past the bearings bymeans of suitable seals 49, respectively, carried by the bearings. Inthis connection it will be noted that fluid pressure is prevented fromescaping in either direction past the piston by seals 50 and 5|,respectively, secured to the top and bottom of the piston by suitablefastener elements. These seals are channel shaped in cross section andthe opposite flanges thereof respectively slidably engage the adjacentwalls of'the cylinder liner 43 and the sleeve I1.

Any suitable means may be employed for alternately supplying fluid underpressure to and exhausting the same from opposite ends of the cylinder4| to effect reciprocation of the piston 40. It will suflice to pointout that when the various parts of the welder are in the relativepositions thereof shown in Figure 2 and it is desired to retract thecylinder head |5 to provide increased clearance below the electrode l0,fluid under pressure is admitted to the cylinder 4| below the piston 4|!and is exhausted from the space in the cylinder 4| above the piston 40.As a result, the piston 40 together with the sleeve I! are moved upwardluntil the bumper 52 on the upper end of the piston engages the bearing'45. The cylinder head I 5 is rigidly connected to the upper end of thesleeve l1 and accordingly moves as a unit with the latter. The piston 20is held against movement relative to the cylinder head by the action ofthe fluid under pressure in the chamber 23 and accordingly this pistontogether with the electrode I0 and associated parts moves upwardly withthe cylinder. The parts are returned to their normal position shown inFigure 2 by exhausting the fluid pressure from the cylinder 4| below thepiston 40 and by supplying fluid under pressure to the cylinder 4| abovethe piston 40. It may be pointed out in this connection that the forceacting on the upperend of the piston 40 to retain the cylinder head andassociated parts in their lowermost positions is suflieient to coun-2,329,851 teract any reactive force tending to raise the 'bracket 55secured to the supporting arm 42 ad jacent the cylinder head I andhaving oppositely disposed side plates 55 which cooperate to form avertical guide. A follower 56 is secured to the cylinder head l5 andslidably engages the inner surfaces of the guide plates 55. As a result,the

guide 53 enables free vertical trave1 of the cylinder head l5 and, atthe same time, prevents rotative movement of the head and associatedparts:

It is also advantageous to prevent rocking movement of the electrode I6relative to its cooperating fixed electrode 51. This is accomplished bya vertical guide 58 comprising a bracket 59 secured to the electrodesupporting structure by means of bolts 60 and having side plate 6|forming a vertical track for receiving a vertical, guide member 62. Theguide member 62 is secured to the adjacent side of the cylinder 5| andis, accordingly, fixed with respect to the bracket 59. This constructionpermits the required retracting movement of the electrode but preventsoscillation of the electrode.

In the present instance'the cylinder head I5 is in the form of a castinfashioned to provide a housing for all of the various instrumentalitiesemployed in the control means for both the welding circuit and electrodeoperating piston 26. These instmmentalities are shown in Figure 3 of thedrawings and operate to perform their respective functions insubstantially the same manner described in detail in the Platz copendingapplication, Serial No. 363,936, filed November 1,

Briefly, the control mechanismv comprise a plunger type valve 65supported between the fluid pressure supply line 66 and the upperend ofthe cylinder l5. The valve 65 is movable to its open position by asolenoid 61 which, in turn, is energized by a suitable switch (notshown) conveniently located for manipulation by the operator. Movementof the valve 65 to its open position shown in Figure 3 establishescommunication between the fluid pressure supply line 66 and the upperend of the cylinder I5,through the me- A the electrode III with thework. a

"It will also be noted from Figure 3 that a second passage IIIestablishes communication between the upper end of the cylinder 15 andthe discharge side of the valve 65 in advance of the metering valve 69.As a result, fluid under the full line pressure isadmitted to thepassage Ill. The flow of fluid under pressure from the passage I6 intothe cylinder I5 is controlled by 9. normally closed. plunger valve 'Ilhaving the upper end communicating with the passage 66 and normally heldclosedagainst the pressure in the passage 68 by a spring I2. Undernormal conditions of operation, the spring I2 is adjustedto maintain thepassage III closed until the electrode I6 has been moved by the piston26 into engagement with the work and, in some instances, opening of thevalve II is delayed until after the welding operation. In cases'oi' thischaracter thefull line pressure admitted to the cylinder through the 75cylinder, a piston in said cylinder normally held passage I6 is employedto forge the work subsequent to the welding operation.

The support to the electrodes is controlled by a fluid pressure operatedswitch I3 having spaced chambers I5 and I5 and having a contact carryingplunger I6 reciprocably mounted between the chambers. The switch I3 isclosed in response to fluid under pressure built up in the chamber I5and accordingly the latter communicates with the passage I0 through themedium of a passage 11. The passage 11 is controlled by a plunger typevalve I8 similar to the valve 'II and is also operated by fluid underpressure from the supply passage 68. However, the valve I6 is adjustedto open as soon as the electrode I0 properly engages the work and servesto supply fluid under pressure to the switch closing chamberindependently of the valve II. The flow of fluid under pressure into thechamber I5 is regulated by a metering valve I9 which is adjustable tocooperate with the valve I6 to effect closing of the welding circuit atthe proper time.

It will also be noted from Figure 3 that fluid pressure from thedischarge side 'of the valve I6 is supplied to the switch openingchamber 15 through a metering valve 86 and an accumulating chamber 8|.The metering valve 66 regulates the rate of pressure rise in theaccumulating chamber 8| and the latter communicates directly with theswitch opening chamber I6 to effect operation of the switch I3 to openthe welding circuit in proper timed relation to closing of this circuit.It may be pointed out that the area of the switch operating plunger I6exposed to the interior of the chamber I4 exceeds the area of theplunger exposed to the switch closing chamber I5 and this differentialis suflicient to enable opening of the switch against the pressure inthe chamber I5.

The valve is returned to its closed position by fluid under pressuresupplied by an accumulating chamber 82. This chamber communicates withthe upper end of the cylinder I5 through the medium of a metering valve69 and a passage 84. The metering valve 69 controls the flow of fluidunder pressure into the accumulating chamber 62 and is adjusted to delayclosing of the valve 65 until the welding cycle is completed. The valveconstruction is such that the end of the valve exposed to the fluidunder pressure from the accumulating chamber 62 is of greater area thanthe area of the valve acted upon by the fluid under pressure flowingthrough the supply line 66 and this difierential area is such as toenable closing of the valve 65 when the required pressure is reached. inthe accumulating chamber 62. It may also be pointed out at this timethat movement of the valve 65 to its closed position opens an exhaustport 65 and enables the system to exhaust. In the present instance,exhaust of the system is facilitated by a valve 66 and by the exhaustport 6I which is opened as soon as the valve 65 is closed.

All of the above parts of the control system are compactly supported inthe cylinder head I! and are. retractible as a unit with the head I 6upon movement of the retracting piston 66 in an upward directionrelative to the fixed cylinder 6|. As a result, the number of flexibleconduits or connections required are reduced to the minimum and theadjustable instrumentalities of the in a retracted position adjacent oneend of the 7 cylinder and movable by fluid under pressure in a directiontoward the other end of the cylinder, an electrode connected to thepiston for movement thereby into engagement with the work to be welded,a second piston concentric with the axis of the first piston andconnected to said head, and means operable in the retracted position ofthe first piston and electrode to move the second piston in a directionto displace the head together with the first piston and electrode in adirection to increase the clearance between the work and electrode.

2. A welder having a head provided with a cylinder and having anelectrode, a piston reciprocably mounted in the cylinder and connectedto the electrode for moving thelatter into and out of engagement withthe work to be welded, means for normally maintaining the piston andelectrode in their retracted positions, means for periodically movingthe piston against the action of the last named means to move theelectrode into contact with the work, a second cylinder concentricallyarranged with respect to the axis of the first cylinder, a pistonreciprocably mounted in the second cylinder and secured to the head, andmeans selectively operable in the retracted position of the first pistonand electrode to move the second piston in a direction to raise the headtogether with the first piston and electrode to increase the clearancebetween the electrode and work.

3. A welder having an electrode and a vertically movable head providedwith a cylinder, a piston reciprocably mounted in the cylinder andnormally maintained in its uppermost position in the cylinder, aconnection between the piston and electrode for moving the latter intoand out of contact with the work to be welded upon movement of thepiston toward and away from the lower end of the cylinder, a verticallyreciprocable sleeve secured at its upper end to the head, a bracketslidably supporting the sleeve and having a portion coacting with thesleeve to form a. cylinder, and a piston reciprocably mounted in thesecond cylinder and secured to the sleeve for raising and lowering saidhead.

4. A welder having an electrode and a vertically movable head providedwith a cylinder, a piston reciprocably mounted in the cylinder andnormally maintained in its uppermost position in the cylinder, aconnectionbetween'the piston and electrode for moving the latter intoand out of contact with the work to be welded upon movement of thepiston toward and away from the-lower end of the cylinder, a verticallyreciprocable sleeve secured at its upper end to the head, a brackethaving vertically spaced bearing portions slidably engaging the sleeveto support the latter and having a portion between the bearing portionscooperating with the sleeve to form a cylinder, a piston reciprocablymounted in the second cylinder and secured to the sleeve for raising andlowering the head, and cooperating slidably engaging means on thebracket and head to prevent rotative movement of the head.

5. A welder having electrode supporting means and having a verticallymoyable head provided with a cylinder, a piston reciprocably mounted inthe cylinder and normally urged to its uppermost position in thecylinder, a connection between the piston and electrode for moving thelatter into and out of contact with the work to be welded upon movementof the piston toward and away from the lower end of the cylinder, a

vertically reciprocable sleeve secured at its upper end to the head, abracket slidably supporting the sleeve and having an annular portioncooperating with the sleeve to form a cylinder, a piston reciprocablymounted in the second cylinder and secured to the sleeve for raising andlowering the head, and selectively operable means for alternatelyintroducing fluid under pressure into and for exhausting fluid underpressure from the second cylinder at opposite sides of the pistontherein.

6. A welder having electrode supporting means and having a verticallymovable head provided with a cylinder, a piston reciprocably mounted inthe cylinder and normally urged to its uppermost position in thecylinder, a connection between the piston and electrode for moving thelatter into and out of contact with the work to be welded upon movementof the piston toward and away from the lower end of the cylinder, avertically reciprocable sleeve secured at its upper end to the head, abracket slidably supporting the sleeve and having an annular portioncooperating with the sleeve to form a cylinder, a piston reciprocablymounted in the second cylinder and secured to the sleeve for raising andlowering the head, cooperating slidably engaging means on the bracketand head preventing rotative movement of the head. relative to thebracket, means on the bracket and electrode supporting means to hold thelatter from rotative movement relative to the bracket.

7. A welder having a vertically movable cylinder and having electrodesupporting means spaced below the cylinder, a piston reciprocablymounted in the cylinder and normally maintained in its uppermostposition in the cylinder,"

a bracket having an annular portion located between the cylinder andelectrode supporting means in concentric relation to the axis of thecylinder, a sleeve slidably supported in the annular portion of thebracket and secured at its upper end to the cylinder, means extendingthrough the sleeve for connecting the piston to the electrode supportingmeans, and means for selectively raising the sleeve to lift the cylindertogether with the piston and electrode supporting able to connect thepiston to the electrode supporting means, and a piston reciprocablymounted in the space between the annular portion of the bracket andsleeve and secured to the latter for raising and lowering the cylinder,associated piston and electrode supporting means.

9. A welder having a vertically movable cylinder and having electrodesupporting means spaced below the cylinder, a piston reciprocablymounted in the cylinder and normally maintained in its uppermostposition in the cylinder,

'a bracket having an annular portion located between the cylinder andelectrode supporting and cooperating slidably engaging.

means in concentric relation the axis of the cylinder, a sleeve slidablysupported in the annular portion of the bracket and secured at its upperend to the cylinder, means slidably supported in the sleeve andoperatively connecting the piston to the electrode supporting means,means for selectively operating the sleeve to raise and lower thecylinder,- associated piston and electrode supporting means, and meanson said bracket and respectively slidably engaging the cylinder andelectrode supporting means to hold both the latter elements fromrotative move- 'ment relative to the bracket.

10. A welder having a vertically movable cylinder and having electrodesupporting,means spaced below the cylinder, a piston reciprocablymounted in the cylinder and normally maintained in its uppermostposition in the cylinder, a bracket having an annular portion locatedbetween the cylinder and electrode supporting means in concentricrelation to the axis of the cylinder, a sleeve slidably supported in theannular portion of the bracket and securedat its upper end to thecylinder, a plunger extending through the sleeve and having its lowerend secured to the electrode supporting means, a yielding connectionbetween the upper end of the the work.

HENRY THOMAS PLATZ.

